1. Field of the Invention
The present invention relates to the structure of fixing a cartridge to the carriage of an ink jet recording apparatus, and also, relates to the structure of the cartridge.
Here, in order to describe the relationship between the fixing point and the fixing force when the cartridge is mounted on the carriage, it is defined in the specification hereof that the thrust direction of the guide shaft that guides the carriage as the direction X; the carrying direction of a recording medium as the direction Y; and the direction perpendicular to the surface of the recording medium as the direction Z, and that the rotational directions centering on these three axes as θX, θY, and θZ, respectively.
Also, in the specification hereof, the phrase “electrical connection” indicates the state where electrical connection is made, and the phrase “ink connection” indicates the state where the ink receiving portion of a cartridge and a needle are connected in order to supply ink to the cartridge.
2. Related Background Art
The ink jet recording technology is such as to record characters and images directly on a recording medium (such as paper, cloth, plastic sheet) by discharging ink from fine nozzles thereto. Conventionally, the recording apparatus having a recording head of ink jet recording type has been utilized as a printer serving as the output terminal of a copying machine, a facsimile equipment, a printer, a word processor, a work station, or the like or as a handy or potable printer used for such an information processing system as a personal computer, a host computer, an optical disc device, a video apparatus. For the conventional ink jet recording apparatus of the kind, there has been known the one in which an ink jet recording head and an ink tank are formed integrally or the one that uses the ink jet cartridge provided with an ink tank arranged to be detachably mountable on the cartridge. The cartridge of the kind is fixedly supported on the carriage mounted on the ink jet recording apparatus main body to be able to perform scanning reciprocation, while being arranged to be of disposable type, which is detachably mountable on the carriage.
FIG. 16 is a perspective view that schematically shows one example of the vicinity of the carriage of the conventional ink jet recording apparatus. FIGS. 17A and 17B are perspective view that illustrate one structural example of the conventional cartridge of disposable type. FIG. 18 is a perspective view that shows the cartridge represented in FIGS. 17A and 17B, observed from the lower front side thereof.
The carriage 152 of the conventional ink jet recording apparatus is structured to support the cartridge 151 to be detachably mountable. Then, on the inner wall thereof, there are arranged plural electrodes 161. Also, the carriage 152 reciprocates along the guide shafts 154 and 159 for scanning in the direction X which is substantially at right angles to the direction Y in which a recording medium 160 is being carried by use of conveyance means (not shown).
The cartridge 151 comprises plural ink tanks 171, each of which is independently arranged to contain color ink mostly inside thereof each corresponding to color print; a holder 170 that holds the ink tanks 171; and the recording head 172 that discharges ink.
As the recording head 172, there is the one that uses electromechanical converting element, such as piezoelectric element, the one that uses electrothermal converting element, such as heat generating resistive element, or the one that uses magnetic wave mechanical converting element or magnetic wave thermal converting element, such as electric wave or laser, which can be utilized for discharging ink droplets from nozzles. Of the heads of the kinds, the one adopting the method to utilize thermal energy for discharging ink droplets is advantageous in that recording is executable in high resolution, because this method makes it possible to arrange nozzles in high density.
The front face 174 of the holder 170 has a head base plate 173 fixed thereto with plural electric connectors 175 connected electrically with the flexible cable that supplies electric energy to the recording head 172. For the holder 170, plural ribs 176 are formed to be extended in the direction substantially perpendicular to the head base plate 173 fixed to the front face 174.
The cartridge 151 is inserted into the carriage 152 from the opening portion 177, and fixed inside the carriage 152 by rotating the head set lever 153 in the direction indicated by an arrow a. Then, the abutting point 166 of the cartridge 151 abuts against the θZ rotation stop point 163 each arranged at two locations, the left and right sides of the inner wall of the carriage 152, and the head base plate 173 is received with the reaction force of the electrodes 161 being depressed to the electrodes 161 centering on them. The cartridge 151 is drawn into the electrode 161 side by the toggle mechanism by rotating the head set lever 153 further in the direction indicated by the arrow a, and abuts against the θX rotation stop point 162 to fix the carriage 152. The conventionally exemplified cartridge 151 is fixed to the carriage 152 at these three points, the θZ rotation stop points 163 on the left and right sides, and the θX rotation stop point 162.
The holder 170 of the cartridge 151 thus fixed to the carriage 152 receives reaction force from the electrodes 161, but the ribs 176 prevent the holder 170 from being deformed by such reaction force. Then, with the support by the ribs 176 over the front face 174, the head base plate 173 is not deformed to make it possible to connect electrically the electric connectors 175 and the electrodes 161 of the carriage 152 stably.
In recent years, however, the multiple use of ink for a color printer has advanced in order to record in higher quality, and the numbers of recording element to be used is increased, while the length of nozzles is made larger to implement higher recording. As a result, the recording area of the recording head is expanded. Along with this, the area of the head base plate is expanded with the increased numbers of electric connectors corresponding to the increased numbers of nozzles. However, it becomes more difficult for a plate member like the head base plate to keep robustness, as the area thereof is made wider. Also, in order to receive the supply of electric power through the pressurized contact with the electrodes of the carriage, it may be impossible to receive the electric supply stably unless suppressed with reaction force of as much as approximately 69 kN at the maximum if each pin is suppressed with reaction force of 490 N.
Fundamentally, ribs are provided for the inside of the holder in order to suppress the deformation of the head base plate and the head partition wall that serves as the front face of the holder, which may be caused by the pressure thus added. However, the ribs are extended from the bottom face of the inner wall of the holder toward the head partition wall, and the power that supports the head base plate is small. There is no problem if a head base plate is small even if ribs are extended from the bottom face of the holder only to a portion nearby. If the area of head base plate becomes larger than the conventional one, the area of the head partition wall that should be supported becomes larger accordingly as a matter of course, and it becomes extremely difficult to support the head base plate including the wide area of the partition wall only by the ribs extending from the bottom face of the head without creating any deformation.
Also, as described above, if the cartridge having the head base plate that needs a large fixing force, as it becomes larger, should be fixed to a carriage, the power added to the head set lever should be larger or the head set laver should be made larger in order to implement the exertion of pressure over the reaction force received by the carriage from the electrodes of the carriage. Nevertheless, if the force that should be added to the head set lever is made larger, its operability becomes unfavorable due to the increased force needed for operation or there is a fear that such force exceeds the limit of stress of the head set lever that has been formed by molding. On the other hand, if the arm of the head set lever is made longer while setting the force to be added to the head set lever at an appropriate value, the size of the cartridge should be made larger to ensue in making the apparatus larger accordingly. Also, if the force that should be added to the head set lever becomes larger, there is a fear that the deformation of the cartridge and head base plate is made greater.
Also, the main body portion of the cartridge is often molded for formation, and along with the trend that it becomes larger, molding deformation is no longer negligible.
Further, in recent years, the number of nozzles of the discharge unit is made larger in order to shorten the recording time, and the length of nozzle is made larger, the amount of ink per discharge becomes as fine as several pl, which requires the precise installation of cartridge of several tens micron order with respect to a recording medium.
The preciseness of the kind is determined by the precision of the mechanism for carrying a recording medium, the precision of the guide shaft for the carriage that reciprocates across the recording medium, the precision of the positioning point of the carriage with respect to the cartridge, and the precision with which the cartridge is made.
Particularly, the deviation of impact of ink on a recording medium in the direction with the vertical axis as the center of rotation generates the displacement of ruled lines or deviation of color formation. The precision in different directions may also contribute to the aforesaid impact deviation as a matter of course, but the greatest cause for this impact deviation is the precision with which nozzles are installed in the rotational direction centering on a recording medium and the vertical axis.
For the conventional head, the θX rotation stop is arranged only at one point in the center above the electric connectors. This location is the center of beam, observed from the cartridge main body, and the portion where deformation becomes greatest. Positioning at the location where the deformation is greatest itself is unfavorable, and worst if some unexpected event may take place or it should be taken into consideration that deformation may possibly exceed the limit of elasticity.
Even at present, there is a need for providing the parallelism of approximately 20 micron if the receiving portion of the carriage is taken into the measurement criterion with respect to the guide shaft for a printer of high image quality. However, this precision is a limit even now, and it takes a long time to achieve the degree of this precision, and also, it tends to be unstable to make the control complicated. Therefore, it is extremely difficult to attain any higher precision in this respect.
Also, for the high image quality printer, not only high speed recording is required, but also, the design consideration begins to be needed for the use thereof at a site where a large scale recording is executed. Consequently, such a disposable type as exemplified for the conventional art presents disadvantage in terms of the weight when an ink tank of a large capacity should be mounted on a movable unit. To cope with the situation, it becomes necessary to adopt the mode in which an ink tank of a large capacity is not mounted on a carriage, but use a tube to connect them, through which ink is supplied from the ink tank to a recording head. FIG. 19 is a perspective view that schematically shows one example of the ink jet recording apparatus structured to have such an ink tank of large capacity fixed on the recording apparatus main body side. As shown in FIG. 19, the structure is arranged so that ink is supplied from the main tank 104 fixed to the recording apparatus main body side to the cartridge 101 mounted on the carriage 102 through the tube 106.
For a recording apparatus of the kind, there is disclosed the recording apparatus in the specification of Japanese Patent Application Laid-Open No. 10-128992, which is structured to connect the tube at the same time when cartridges are replaced. The recording apparatus thus disclosed in the specification thereof makes it possible to complete the connection of the tube simultaneously with the insertion of the cartridge into the carriage. However, since the electrical connection and the tube connection are executed at the same time, the direction in which pressure is exerted to position the cartridge and the direction in which the inserting force is exerted together with the electrical connection are caused to vary. Also, in accordance with the example disclosed in the aforesaid specification, the cartridge is structured to be one line/one color, and there is no problem as to the robustness of the cartridge. For example, however, if six-line nozzles are mounted on one piece of cartridge, the electrical connection and ink connection portions are increased, and the load is increased accordingly, while the span of the robust wall face of the member that forms the cartridge is elongated to make it conceivably difficult to keep the required robustness. In other words, the precision with the cartridge should be installed is inevitably reduced, and it is conceivable that a problem is encountered that the impact precision is degraded eventually.